Objects can be located and tracked with a system that receives radio frequency (RF) signals transmitted by electronic tags attached to the objects. The tags are sometimes referred to as radio frequency identification (RFID) tags. By receiving and triangulating the RF signals, the system can determine the location of each tagged object and determine whether it has changed locations, i.e., it can track the object.
Such systems have been used to track various types of objects. However, the majority of such tracking systems are used to track objects that do not rapidly change location, such as file folders in an office environment, or medical equipment and patients in a hospital environment. Tracking objects that rapidly change location presents additional technical difficulties.
An example of such a known tracking system includes a number of spread-spectrum radio receivers placed at locations around a playing field that track tags attached to athletes such as football players. The system performs time-of-arrival (TOA) or relative signal level calculations upon the signals to estimate the locations from which the signals originated and thus the locations of the tagged players.